I have a V6 Formula I just purchased The car did not have much power, stumbled a little. I changed the plugs, wires, rotor and cap. I set the timing to 10 BTDC. It ran OK for a few days but lost power and started backfiring and won't idle.
I checked the timing and it was very advanced and off the scale. I cannot pull the timing back to get it to the marks. I turned the distributor all the way till it reached the mechanical limits.
The distributor bolt was very tight, so it does not seem likely that the distributor slipped.
Does this sounld like a loose or jumped timing chain?
Sounds like you might not have disabled the ECM's timing advance. 10BTDC is the base timing, without the ECM adding to it. You have to jumper a couple pins on the diagnostic connector before you can check the base timing. (explained in detail in the video posted above).
Automatic or 5-speed? Auto are supposed to be timed in gear, not in neutral. Gotta find a sidewalk or something to pull your car up against so it won't run away.
What? Can you support that claim by anything legitimate from GM, such as an officail shop manual (Helm)? As an extension, why would an auto have the timing set under load? Why not a manual equipped car? It's the same engine in both.
The car is a 5-speed. I put the paper clip in and got the flashing check engine light to confirm it was in base timing mode. I need to go back and rotate the engine to make sure I actually tried to set timing to the actual "0" mark. I think it was the wide mark but that is a good thing to check.
What? Can you support that claim by anything legitimate from GM, such as an officail shop manual (Helm)?
The factory service manual only says to refer to the specs on the emissions sticker.
As per the '88 V6 emissions sticker, the correct timing is 10 degrees before TDC in "D" for cars with an automatic trans, and in "N" for a stick. However, I doubt many people really do it in Drive. I don't.
I think it was the wide mark but that is a good thing to check.
Yeah, make sure its the right mark. The thin marks are 120 degrees on either side of the wide mark.
Also be aware a few people have had cars where the outer ring on the harmonic balancer has slipped. Its just pressed onto the hub with a sleeve of hard rubber than can deteriorate over time and make the ring slip.